feat: warn user before losing progress on an unfinished practice (#277)

Co-authored-by: Nathan Lovato <[email protected]>

autoload/NavigationManager.gd

@@ -1,16 +1,26 @@
 extends Node
 
-signal navigation_requested()
-signal back_navigation_requested()
-signal outliner_navigation_requested()
-signal welcome_screen_navigation_requested()
+signal navigation_requested
+signal back_navigation_requested
+signal outliner_navigation_requested
+signal welcome_screen_navigation_requested
+signal last_screen_unload_requested
+signal all_screens_unload_requested
+
+enum UNLOAD_TYPE { BACK, OUTLINER }
+
+const ERROR_WRONG_UNLOAD_TYPE := "Unsupported unload type in NavigationManager! Unload type: %s"
 
-var _url_normalization_regex := RegExpGroup.compile("^(?<prefix>user:\\/\\/|res:\\/\\/|\\.*?\\/+)(?<url>.*)\\.(?<extension>t?res)")
 var history := PoolStringArray()
 var current_url := "" setget set_current_url, get_current_url
 var is_mobile_platform := OS.get_name() in ["Android", "HTML5", "iOS"]
 var arguments := {}
 
+var _current_unload_type := -1
+var _url_normalization_regex := RegExpGroup.compile(
+	"^(?<prefix>user:\\/\\/|res:\\/\\/|\\.*?\\/+)(?<url>.*)\\.(?<extension>t?res)"
+)
+
 
 func _init() -> void:
 	_parse_arguments()
@@ -21,6 +31,7 @@ func _init() -> void:
 		if initial_url != "":
 			navigate_to(initial_url)
 
+
 func _parse_arguments() -> void:
 	arguments = {}
 	for argument in OS.get_cmdline_args():
@@ -31,29 +42,86 @@ func _parse_arguments() -> void:
 			arguments[key] = value
 
 
+# Checks if any resource with active user data is about to be closed.
+#
+# If the current screen is a Practice it might have code edited. If the current
+# screen is a Lesson it might be shadowing a Practice.
+func _is_unload_confirmation_required() -> bool:
+	# For the home screen and outliner, get_current_url() returns "". We use
+	# that to return false for those screens.
+	if get_current_url():
+		var resource = get_navigation_resource(get_current_url())
+		return resource is Practice or resource is Lesson
+
+	return false
+
+
 func get_history(n := 1) -> String:
 	if n > history.size():
 		return ""
 	return history[history.size() - n]
 
 
+# Called by any screen that is to be unloaded (but it is not safe/user denied)
+func deny_unload() -> void:
+	_current_unload_type = -1
+
+
+# Called by any screen that is to be unloaded
+func confirm_unload() -> void:
+	match _current_unload_type:
+		UNLOAD_TYPE.BACK:
+			_navigate_back()
+		UNLOAD_TYPE.OUTLINER:
+			_navigate_to_outliner()
+		_:
+			printerr(ERROR_WRONG_UNLOAD_TYPE % _current_unload_type)
+
+	_current_unload_type = -1
+
+
+# Call to navigate back from within the app. If the user is about to lose data,
+# they'll get a popup window preventing them from navigating back until they
+# confirm they want to leave the screen.
+#
+# For browser-only navigation, use _navigate_back() instead.
 func navigate_back() -> void:
+	if _is_unload_confirmation_required():
+		_current_unload_type = UNLOAD_TYPE.BACK
+		emit_signal("last_screen_unload_requested")
+		return
+
+	_navigate_back()
+
+
+func navigate_to_outliner() -> void:
+	if _is_unload_confirmation_required():
+		_current_unload_type = UNLOAD_TYPE.OUTLINER
+		emit_signal("all_screens_unload_requested")
+		return
+
+	_navigate_to_outliner()
+
+
+# Navigates back instantly, without confirmation popups. Use this for browser
+# navigation.
+func _navigate_back() -> void:
 	# Nothing to go back to, open the outliner.
 	if history.size() < 2:
 		navigate_to_outliner()
 		return
 
 	history.remove(history.size() - 1)
 	_js_back()
-	
+
 	emit_signal("back_navigation_requested")
 
 
-func navigate_to_outliner() -> void:
+func _navigate_to_outliner() -> void:
 	# prints("emptying history")
 	history.resize(0)
 	_js_to_outliner()
-	
+
 	emit_signal("outliner_navigation_requested")
 
 
@@ -64,41 +132,41 @@ func navigate_to_welcome_screen() -> void:
 func navigate_to(metadata: String) -> void:
 	var regex_result := _url_normalization_regex.search(metadata)
 	if not regex_result:
-		push_error("`%s` is not a valid resource path"%[metadata])
+		push_error("`%s` is not a valid resource path" % [metadata])
 		return
 	var normalized := NormalizedUrl.new(regex_result)
-	
+
 	if not normalized.path:
 		push_error("`%s` is not a valid path" % metadata)
 		return
-	
+
 	var file_path := normalized.get_file_path()
-	
+
 	var resource := get_navigation_resource(file_path)
 	if not (resource is Resource):
 		push_error("`%s` is not a resource" % file_path)
 		return
-	
+
 	history.push_back(file_path)
 	_push_javascript_state(normalized.get_web_url())
 
 	emit_signal("navigation_requested")
 
 
-func get_navigation_resource(resource_id : String) -> Resource:
+func get_navigation_resource(resource_id: String) -> Resource:
 	var is_lesson := resource_id.ends_with("lesson.tres")
-	
+
 	if is_lesson:
 		return load(resource_id) as Resource
-	
+
 	var lesson_path := resource_id.get_base_dir().plus_file("lesson.tres")
 	var lesson_data := load(lesson_path) as Lesson
-	
+
 	# If it's not a lesson, it's a practice. May support some other types in future.
 	for practice_res in lesson_data.practices:
 		if practice_res.practice_id == resource_id:
 			return practice_res
-	
+
 	return null
 
 
@@ -155,10 +223,10 @@ func _on_init_setup_js() -> void:
 	if not _js_available:
 		return
 	_js_history = JavaScript.get_interface("history")
-	
+
 	# if the reference doesn't survive the method call, the callback will be dereferenced
 	_js_popstate_listener_ref = JavaScript.create_callback(self, "_on_js_popstate")
-	
+
 	_js_window = JavaScript.get_interface("window")
 	# warning-ignore:unsafe_method_access
 	_js_window.addEventListener("popstate", _js_popstate_listener_ref)
@@ -167,19 +235,21 @@ func _on_init_setup_js() -> void:
 	var url: String = (
 		# warning-ignore:unsafe_property_access
 		# warning-ignore:unsafe_property_access
-		_js_window.location.hash.trim_prefix("#").trim_prefix("/") if _js_window.location.hash else ""
+		_js_window.location.hash.trim_prefix("#").trim_prefix("/")
+		if _js_window.location.hash
+		else ""
 	)
 	if url:
-		navigate_to("res://%s"%[url])
+		navigate_to("res://%s" % [url])
 
 
 # Handles user changing the url manually or pressing back
 func _on_js_popstate(_args: Array) -> void:
 	# we have set this to `false` either in _js_to_outliner or _js_back, we can set it back to true now
 	if _temporary_disable_back_listener:
 		return
-	# var event = args[0]
-	navigate_back()
+	_navigate_back()
+
 
 # Call this from GDScript to synchronize the browser. Safe to call in all environments, will no-op
 # when JS is not available.
@@ -213,13 +283,15 @@ func _restore_popstate_listener() -> void:
 	yield(get_tree().create_timer(0.3), "timeout")
 	_temporary_disable_back_listener = false
 
+
 # Call this from GDScript to synchronize the browser. Safe to call in all environments, will no-op
 # when JS is not available.
 func _push_javascript_state(url: String) -> void:
 	if not _js_available:
 		return
 	# warning-ignore:unsafe_method_access
-	_js_history.pushState(url, '', '#'+url)
+	_js_history.pushState(url, "", "#" + url)
+
 
 class NormalizedUrl:
 	var protocol := ""
@@ -232,13 +304,12 @@ class NormalizedUrl:
 		extension = regex_result.get_string("extension")
 		if protocol in ["//", "/"]:
 			protocol = "res://"
-
-
+
 	func get_file_path() -> String:
-		return "%s%s.%s"%[protocol, path, extension]
-	
+		return "%s%s.%s" % [protocol, path, extension]
+
 	func get_web_url() -> String:
-		return "%s.%s"%[path, extension]
+		return "%s.%s" % [path, extension]
 
 	func _to_string() -> String:
 		return protocol + path

project.godot

@@ -239,17 +239,22 @@ _global_script_classes=[ {
 "language": "GDScript",
 "path": "res://ui/screens/lesson/UIContentBlock.gd"
 }, {
-"base": "Control",
+"base": "UINavigatablePage",
 "class": "UILesson",
 "language": "GDScript",
 "path": "res://ui/UILesson.gd"
 }, {
+"base": "Control",
+"class": "UINavigatablePage",
+"language": "GDScript",
+"path": "res://ui/UINavigatablePage.gd"
+}, {
 "base": "PanelContainer",
 "class": "UINavigator",
 "language": "GDScript",
 "path": "res://ui/UINavigator.gd"
 }, {
-"base": "Control",
+"base": "UINavigatablePage",
 "class": "UIPractice",
 "language": "GDScript",
 "path": "res://ui/UIPractice.gd"
@@ -327,6 +332,7 @@ _global_script_class_icons={
 "UIBaseQuiz": "",
 "UIContentBlock": "",
 "UILesson": "",
+"UINavigatablePage": "",
 "UINavigator": "",
 "UIPractice": "",
 "UIPracticeButton": "",

ui/UILesson.gd

@@ -4,7 +4,7 @@
 # When pressing a practice button, emits an event so the navigation can
 # transition to the practice screen.
 class_name UILesson
-extends Control
+extends UINavigatablePage
 
 const ContentBlockScene := preload("screens/lesson/UIContentBlock.tscn")
 const QuizInputFieldScene := preload("screens/lesson/quizzes/UIQuizInputField.tscn")

ui/UINavigatablePage.gd

@@ -0,0 +1,52 @@
+# Base class for lesson and practice pages. Provides an interface for navigation
+# in relation with NavigationManager.
+#
+# Defines required overridable functions for interaction with
+# NavigationManager.gd.
+#
+# Defaults to always accept being unlaoded unless overriden.
+class_name UINavigatablePage
+extends Control
+
+var _is_current_screen := false
+
+
+func _ready() -> void:
+	NavigationManager.connect(
+		"all_screens_unload_requested", self, "_on_all_screens_unload_requested"
+	)
+
+
+func set_is_current_screen(value: bool) -> void:
+	if _is_current_screen == value:
+		return
+
+	_is_current_screen = value
+
+	if _is_current_screen:
+		NavigationManager.connect(
+			"last_screen_unload_requested", self, "_on_current_screen_unload_requested"
+		)
+	else:
+		NavigationManager.disconnect(
+			"last_screen_unload_requested", self, "_on_current_screen_unload_requested"
+		)
+
+
+func _accept_unload() -> void:
+	NavigationManager.confirm_unload()
+
+
+func _deny_unload() -> void:
+	NavigationManager.deny_unload()
+
+
+# Overridde if unload requires waiting
+func _on_current_screen_unload_requested() -> void:
+	_accept_unload()
+
+
+# Overridde if unload requires waiting
+func _on_all_screens_unload_requested() -> void:
+	if _is_current_screen:
+		_on_current_screen_unload_requested()

ui/UINavigator.gd

@@ -99,14 +99,16 @@ func _navigate_back() -> void:
 		_navigate_to_outliner()
 		return
 
-	var current_screen: Control = _screens_stack.pop_back()
-	var next_screen: Control = _screens_stack.back()
+	var current_screen: UINavigatablePage = _screens_stack.pop_back()
+	var next_screen: UINavigatablePage = _screens_stack.back()
 	_update_back_button(_screens_stack.size() < 2)
 
 	# warning-ignore:unsafe_method_access
 	var target = next_screen.get_screen_resource()
 	_breadcrumbs.update_breadcrumbs(course, target)
 
+	next_screen.set_is_current_screen(true)
+
 	_transition_to(next_screen, current_screen, false)
 	yield(self, "transition_completed")
 	current_screen.queue_free()
@@ -135,7 +137,7 @@ func _navigate_to_outliner() -> void:
 # Navigates forward to the next screen and adds it to the stack.
 func _navigate_to() -> void:
 	var target := NavigationManager.get_navigation_resource(NavigationManager.current_url)
-	var screen: Control
+	var screen: UINavigatablePage
 	if target is Practice:
 		var lesson = course.lessons[_lesson_index]
 
@@ -160,12 +162,14 @@ func _navigate_to() -> void:
 
 	var has_previous_screen = not _screens_stack.empty()
 	_screens_stack.push_back(screen)
+	screen.set_is_current_screen(true)
 	_back_button.show()
 	_update_back_button(_screens_stack.size() < 2)
 
 	_screen_container.add_child(screen)
 	if has_previous_screen:
-		var previous_screen: Control = _screens_stack[-2]
+		var previous_screen: UINavigatablePage = _screens_stack[-2]
+		previous_screen.set_is_current_screen(false)
 		_transition_to(screen, previous_screen)
 		yield(self, "transition_completed")